fix(security): close unauthenticated CMA user API surface + audit tool (cma-api-auth-surface-audit-20260914)

Root cause: main.py include_router had no global auth dependency; user routers
(products/cost/predict/...) relied on assert_entity_scope, which treats a
missing session token as the Bot service channel and lets the request through.
Result: 46 user endpoints returned data without any token on a public site.

Changes:
- auth_middleware.py: add require_auth_401 (missing Bearer -> 401, delegates to
  require_auth otherwise); 401/403 semantics are explicit.
- router-level Depends(require_auth_401) on products, cost, predict,
  notifications, permissions, tenant, alignment; endpoint-level on
  /auth/roles and /admin/cache/clear.
- deps.py: document that get_entity_id/assert_entity_scope are NOT auth.
- frontend: add the missing Bearer header to 5 tokenless fetch/axios calls that
  hit the newly protected endpoints (KPIAlignment x2, RolePermissions x2,
  Dashboard x1).
- tests: new test_api_auth_surface_20260914.py (58 cases: no-token 401,
  token 200, cross-entity 403, bot channel unchanged); adapt test_predict /
  test_kpi_forecast to send session tokens like production.
- scripts/audit_api_auth_surface.py: reusable FastAPI dependency-graph audit
  (423 endpoints; A bot / B gap / C public), exits 1 when a B-class gap exists.

frontend/src/views/Dashboard.vue

@@ -482,7 +482,10 @@ async function loadData() {
       finSummary.value = (r as any)?.summary || {}
       dataRange.value = (r as any)?.period || ''
     } else if (userRole.value === 'it') {
-      const channelRes = await axios.get('/api/cma/notifications/channels').then(r => r.data)
+      // 鉴权收口（cma-api-auth-surface-audit-20260914）：/notifications/channels 已要求 Bearer
+      const channelRes = await axios.get('/api/cma/notifications/channels', {
+        headers: { 'Authorization': `Bearer ${localStorage.getItem('cma_token')}` },
+      }).then(r => r.data)
       enabledChannels.value = channelRes.data?.filter((c: any) => c.enabled).length || 0
     }
   } catch (e) { console.error('加载数据失败:', e) }